The development of high quality multimedia devices, such as set-top boxes, high end televisions, digital televisions, personal televisions, storage products, personal digital assistants (PDAs), wireless Internet devices, etc., is leading to a variety of architectures and to more openness towards new features for these devices. The development of these new products and their ability to display video data in any format has resulted in new requirements and opportunities with respect to video processing and video enhancement algorithms. Most of these devices receive and/or store video in the MPEG-2 format.
Next generation storage devices, such as the blue laser based Digital Video Recorder, will have high definition (HD) capability to some extent. A high definition (HD) program is typically broadcast at twenty million bits per second (20 megabits per second or 20 Mb/s) and encoded according to the MPEG-2 video standard. The storage capacity of a Digital Video Recorder is in the range of approximately twenty Gigabytes (20 GB). This represents about two (2) hours of recording time of HD video per video disc.
To increase the amount of record time per video disc, long play modes can be defined. For example, in a Long Play (LP) mode, a broadcast bitrate of twenty megabits per second (20 Mb/s) may be recorded at a storage bitrate of ten megabits per second (10 Mb/s). This will provide about four (4) hours of recording time per video disc. In an Extended Long Play (ELP) mode, a broadcast bitrate of twenty megabits per second (20 Mb/s) may be recorded at a storage bitrate of five megabits per second (5 Mb/s). This will provide about eight (8) hours of recording time per video disc.
The process of recording a bitstream at a lower rate is referred to as “transcoding” the bitstream. One method of transcoding a high bitrate bitstream involves the steps of decoding the high bitrate bitstream with an MPEG-2 decoder, de-interlacing the bitstream, converting to a lower resolution by applying 2D scaling, re-interlacing the bitstream, and encoding the resulting bitstream at the lower bitrate. Another method of transcoding a high bitrate bitstream involves directly transcoding the bitstream to a lower bitrate without fully decoding and re-coding the video. This method is known as Direct Bitrate Transcoding (DBT).
Media processors are capable of transcoding multimedia data in the MPEG format. If a bitrate transcoder of a media processor is able to transcode MPEG video data at the same rate at which the MPEG video data arrives, then the transcoding process is said to be done in “real time.” If the computing resources of the media processor are not sufficient to process the MPEG video data in real time, then completion of the transcoding process will occur after the arrival of the last portion of the MPEG video data.
Media processors can achieve real time performance levels if the media processing requires minimal computing resources or if the size of the MPEG frames to be processed is small. For example, the Trimedia™ family of media processors (TM1100, TM1300) manufactured by Philips Electronics North America Corporation can perform an MPEG video transform on standard definition (SD) MPEG video data in almost real time. A Trimedia™ processor would require approximately two hundred fifty (250) to three hundred (300) megacycles per second to process high definition (HD) MPEG video data. This level of level of processing power is not presently available.
There is therefore a need in the art for an apparatus and method that will enable presently existing media processors to process high definition (HD) MPEG video data to achieve bitrate transcoding of HD video data in real time.